The auxiliary electric heater activates when the heat pump alone is insufficient or when a specific operating mode requires it.
What to check
Activation setpoint, outdoor temperature, relay or contactor, fuses, and actual voltage at the heater.
Interlocks
The controller may prevent its operation if there is a sensor fault or another active protection.
Diagnosis
We check if the command is missing or if the command is present but power is not reaching the element.
